Room-temperature gas sensors based on titanium dioxide quantum dots for highly sensitive and selective H2S detection

Room-temperature gas sensors with high performance are crucial in practical application. This work prepared a series of controllable-size titanium dioxide quantum dots (TiO2 QDs) via a rapid microwave-assisted solvothermal method for detecting ppb-level H2S at room temperature. The effect of reaction temperature on the nanostructure and gas sensing properties was investigated systematically. The characterization results showed the samples presented ultra-small size (around 5–6 nm) nanostructure and modified surface state (including Ti3+ and oxygen defects). The S120-TiO2 QDs gas sensor showed the best sensing properties towards ppb-level H2S at room temperature, including high response (25.12 @ 500 ppb H2S), rapid response/recovery, low detecting limit level, good selectivity, and operating stability. The gas sensing mechanism was explained through the synergetic effect of ultra-small size nanostructure, large specific surface area, and surface defects, which are in favor of improving the surface activity and charge transfer efficiency. Moreover, the practical application of TiO2 QDs gas sensor in detecting the volatiles of fish (Pangasius) was also verified. This work developed a room temperature TiO2 quantum dots-based gas sensor, which is promised for practical application because of the rapid synthesis and high performance.